FB-ATB very common when people start a keto diet. As above an electrolyte tab usually solves the headache pretty quick. Increasing fluid would also rule out dehydration as a cause as well.
I have knocked off 0.9 kg again this week, without doing anything outrageous, just more veg, less sugar, less processed carbs.
I will be perfectly happy with 0.9 kg every week, that will be 45 kg by this time next year. Annoyingly I still wouldn’t be underweight!
Matt